Reflection of waves from a mobile elastic layer in a multimode waveguide

Waveguide structures are used to transmit energy and information signals in a wide range of wavelengths and, terms wave-guiding physical properties, usually have mutual (identical) properties forward backward directions. The asymmetry the structure external influences can often cause non-reciprocity for waves, propagating mutually opposite directions (this property, although limited, is already so-called nonreciprocal devices microwave, EHF optical ranges such as ferrite valves, circulators, phase shifters). At same time, structures, independent their nature, were not considered. It found, that motion medium filling acoustic waveguide leads nonreciprocity its parameters degree proportional velocity medium. also affects propagation waves change critical frequencies or modes. As increases, number modes which condition satisfied increases well.